Combining calcium, magnesium & potassium

[mikellini]

Hey there, I've been reading a bit on Red Sea's website and they say that for dosing via a dosing pump, their Reef Foundation A & C (calcium and magnesium) and Reef Colours B (Potassium and trace) can be combined. I've emailed them for instructions on how to do this (ratios etc), but I just wanted to ask here if anyone has done this, if it can be done with a DIY recipe or another brand's supplements, and if there are any pro's and cons to doing it this way. Obviously you would want to under-shoot demand for magnesium and potassium a little bit, and would require occasional manual dosing to even out the levels, but other than that I can't see any con's (if it's possible). Anybody?

 

[Randy Holmes-Farley]

Mixing calcium, magnesium and potassium can be done if all are the chloride forms.

But magnesium supplements often and desirably contain some sulfate, and you cannot mix a sulfate with calcium or you'll precipitate calcium sulfate.

As to trace elements, it depends on what they are, but diluting them is often not best as it will encourage oxidation of some of them.

 

[mikellini]

Mixing calcium, magnesium and potassium can be done if all are the chloride forms.

But magnesium supplements often and desirably contain some sulfate, and you cannot mix a sulfate with calcium or you'll precipitate calcium sulfate.

As to trace elements, it depends on what they are, but diluting them is often not best as it will encourage oxidation of some of them.

To be a bit more specific, they list potassium and boron at the main components in Reef Colours B. Also, Reef Foundation A has strontium in addition to calcium, not sure if that makes a difference...

Why again is it desirable to use magnesium sulfate vs magnesium chloride? Is it because it doesn't have an effect on salinity?

I wonder if mixing calcium chloride, magnesium chloride, and potassium iodide is possible (and/or feasible/beneficial). I'm not really too worried about supplementing the other two (strontium and boron), so if I could do it myself then I'd save a bit of money and also dose some iodine. Or is potassium chloride the only way to go?

 

[mikellini]

Just checked, strontium and boron are strontium chloride and sodium tetraborate. I'm assuming the potassium, magnesium and calcium are all chloride.

 

[Randy Holmes-Farley]

Sulfate should be added somehow into a system that supplements calcium and alkalinity (and magnesium).

If not, then it must have excessive chloride, and chloride will rise relative to sulfate. That changes the balance of ions in the seawater to look less and less like natural seawater.

My DIY two/three part has the appropriate amount of sulfate, all coming with the magnesium sulfate, but it doesn't need to come that way, and could be in the alkalinity part of the system.

I expect the Red Sea program has it, but I do not know where, which complicates mixing ideas.

However, you can just try it and see if anything precipitates.

 

[mikellini]

Their MSDS's only show 'hazardous' ingredients, so it doesn't say exactly what's in their alkalinity mix. Or even their magnesium mix. It identifies calcium chloride and strontium chloride in the first mix, and only sodium tetratborate in the Reef Colours B mix (although there must also be some kind of potassium as well).

What happens if the chloride/sulfate ratio changes too much? Is this mitigated by water changes?

EDIT: They state their calcium mix also contains barium apparently. Hmm, that's a lot of other elements... might be worth it just to go with their mix, it would be nice to be able to dose calcium, magnesium, potassium, boron, barium, and strontium all with one pump haha. Just sounds too good to be true...

 

[Randy Holmes-Farley]

The chloride to sulfate ratio is discussed in these articles:

Aquarium Frontiers On-Line: Biochemistry of Aquaria

Aquarium Frontiers Biochemistry of Aquaria

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com

 

[JimWelsh]

What happens if the chloride/sulfate ratio changes too much?

That is a great question, and while the articles Randy linked to do discuss the general subject of maintaining a natural chloride:sulfate ratio, they do not directly address this specific question. I'd like to know, too.

 

[Randy Holmes-Farley]

I've never seen a scientific study of it, probably because it doesn't happen to any great degree in the ocean. But salt mixes have varied considerably over the years without anyone noting a big effect.

So I think it falls into the category of things where we just don't know, and so matching NSW seems a reasonable goal.

In general, it is not something I'd worry about, but when there is a choice to be made, I'd pick to try to be close to a NSW chloride to sulfate ratio.

 

[miamiangler]

Before adding Test Test Test .